U.S. patent number 5,147,611 [Application Number 07/384,805] was granted by the patent office on 1992-09-15 for optical and pyrolyzate analyzer apparatus.
This patent grant is currently assigned to Union Oil Company of California. Invention is credited to Stephen R. Larter, Rui Lin, Gunnar W. Recht, Joseph T. Senftle, Scott A. Stout.
United States Patent |
5,147,611 |
Stout , et al. |
September 15, 1992 |
**Please see images for:
( Certificate of Correction ) ** |
Optical and pyrolyzate analyzer apparatus
Abstract
A heating and targeting laser beam and microscope apparatus
optically senses, heats to generate a effluent fluid and chemically
analyzes the thermal extract fluid or fluid pyrolyzates from a
microscopic particle within a heterogeneous composite sample. A
transparent duct-like chamber having a bottom opening is attached
to a microscope. A contact surface of the sample is raised to abut
against the bottom opening, which encloses the space around the
particle and also brings the particle into the common focal plane
of the microscope and the converging laser beam(s). This single
step avoids the complex separate focusing and sealing steps
required by present day techniques. The apparatus also includes an
insulated and conductively heated collection probe and an inert gas
supply (to efficiently sweep and collect the small amount of hot
fluid and minimize condensation loss, secondary reactions, or
complex heating devices), diverging-collimating-converging laser
beam lenses (to achieve spot focusing as small as 10 microns) and a
cold trap (to collect a series of fluid quantities). A collective
analysis of the trapped fluid generated from a single type of
particle is accomplished on a resolution quantity of fluid
volatilized from the cold trap.
Inventors: |
Stout; Scott A. (Fullerton,
CA), Lin; Rui (Corona, CA), Recht; Gunnar W. (La
Habra, CA), Senftle; Joseph T. (Plano, TX), Larter;
Stephen R. (Venice, CA) |
Assignee: |
Union Oil Company of California
(Los Angeles, CA)
|
Family
ID: |
23518829 |
Appl.
No.: |
07/384,805 |
Filed: |
July 24, 1989 |
Current U.S.
Class: |
422/78; 422/80;
422/82.05; 436/155; 436/181; 436/25; 436/31; 436/32 |
Current CPC
Class: |
G01N
21/71 (20130101); Y10T 436/25875 (20150115) |
Current International
Class: |
G01N
21/71 (20060101); G01N 025/02 (); G01N
033/24 () |
Field of
Search: |
;422/73,78,80,82.05
;436/25,31,32,155,181 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
"Laser Probe System for the Microscale Preparation of Carbonate and
Sulfide Samples for Isotope Ratio Mass Spectrometry" by Arnold R.
Taylor, 1985. .
"Pyrolysis Methods, Pyrolysis Apparatus," pp. 68-71. .
Interlase, Inc., "Instruction Manual Model 303," May, 1983. .
Interlase, Inc. "Instruction Manual Model 303A Accessory Package,"
May, 1983. .
"Application of Laser Microprobe (LAMMA 1000) to Fingerprinting of
Coal Constituents in Bituminous Coal", Lyons et al, in
International Journal of Coal Geology (1987), pp. 185-194, vol. 7,
No. 2. .
"Recent Development With the Laser Microprobe Mass Analyzer
(LAMMA)", by Heinen & Holm, in Scanning Electron
Microscopy/1984/vol. III, pp. 1129-1138. .
"Solid State Mass Spectrometry Using a Laser Microprobe by
Hercules", in Voorhees Analytical Hydrolysis, pp. 1-41, 1982. .
"The Development of Laser Micro Pyrolysis of Coal Macerals", by
Vastgla & McGahan, Americal Chemical Society, Fuel Division
Preprint, 1986, vol. 31(1), pp. 53-56. .
"Compositional and Structural Study of A Coal Surface Using a Laser
Microprobe Mass Detector", by Dutta and Talmi, in Fuel, 1982, vol.
61, Dec., pp. 1241-1244. .
"Using Laser Micro Mass Spectrometry with the Lamma-1000 Instrument
for Monitoring Relative Elemental Concentrations in Vitrinite", By
Morelli et al., Mikrochim. Acta 1988, vol. III, pp. 105-118. .
"Application of the Laser Microprobe (LAMMA 1000) to the
Microanalysis of Coal Constituents", By Lyons et al., New Frontiers
in Stable Isotoyic Research, pp. 97-110. .
"High Precision Spatially Resolved Analysis of .sup.34 S in
Sulphides Using a Laser Extraction Technique", by Kelley and
Fallick, Geochimica et Cosmochimica Acta, vol. 54, pp. 883-888,
1990. .
J. Chromatoga, 56 (1971) 348-352, "Laser Pyrolysis of Oil Shales,"
by Biscar, pp. 348-352. .
"High Energy (Neodymium) Laser Pyrolysis of Coal," by Vanderborgh
et al., LA-UR-81-431, Submitted to Journal of Analytical and
Applied Pyrolysis. .
"Microscope-Laser Pyrolysis-Project Proposal," Jun. 1983, by Solli
et al., Organic Geochemistry Dept., Continental Shelf Institute.
.
"Use of the Laser-Micropyrolysis-Mass Spectrometer in Studying the
Pyrolysis of Coal," Symposium on Pyrolysis Reactions of Fossil
Fuels presented before the Division of Petroleum Chemistry, Inc.,
American Chemical Society Pittsburgh Meeting, Mar. 23-26,
1966..
|
Primary Examiner: Johnston; Jill A.
Attorney, Agent or Firm: Wirzbicki; Gregory F. Jacobson;
William O.
Claims
What is claimed is:
1. An apparatus for analyzing a particle within a sample, said
apparatus comprising:
a sensor capable of detecting emitted radiation from said particle
within a detection zone, said sensor detecting emitted radiation
centered around an axis and said zone located substantially around
a portion of said axis wherein detection sensitivity of said sensor
is substantially at a maximum sensitivity from within said
zone;
a chamber attached to said sensor wherein at least a portion of
said chamber extends along said axis towards said particle, said
chamber having a first chamber aperture located substantially
around said axis;
a contact surface for setting said particle, at least a portion of
said contact surface spaced apart from said particle, said contact
surface shaped and dimensioned to contact a portion of said chamber
located near said first aperture when said particle is within said
zone, wherein said contact surface and the set particle can be
spaced apart from said chamber;
means for changing the relative spacing between said set particle
and said chamber, so that when said contact surface is
substantially contacting said chamber, a partial boundary is formed
around said particle by said chamber and said contact surface;
means for transmitting said emitted radiation from the partially
bounded particle to said sensor;
a source of energy capable of heating said particle until a fluid
emanates from a portion of the partially bounded particle;
means for transferring energy from said energy source to a portion
of the partially bounded particle;
means for collecting said fluid from said chamber.
2. The apparatus of claim 1 wherein said chamber also comprises an
abutting end surface at or near said first aperture.
3. The apparatus of claim 2 wherein said radiation is visible light
and said sensor is a microscope having an objective lens.
4. The apparatus of claim 3 wherein said chamber also comprises a
first window located substantially around said axis and attached to
a second aperture, wherein said first window is transparent to
radiation within the visible frequency band and said window is
located at or near said objective lens.
5. The apparatus of claim 4 wherein said contact surface is a
generally planar surface perpendicular to said axis, wherein said
contact surface is movably mounted to said microscope, said contact
surface capable of moving in a directions perpendicular and
parallel to said axis.
6. An apparatus for analyzing a particle within a sample, said
apparatus comprising:
a sensor capable of detecting emitted radiation from said particle
within a detection zone, said sensor detecting emitted radiation
centered around an axis and said zone located substantially around
a portion of said axis wherein detection sensitivity of said sensor
is substantially at a maximum sensitivity from within said
zone;
a chamber attached to said sensor wherein at least a portion of
said chamber extends along said axis towards said particle, said
chamber having a first chamber aperture located substantially
around said axis;
a contact surface for setting said particle, at least a portion of
said contact surface spaced apart from said particle, said contact
surface shaped and dimensioned to contact a portion of said chamber
located near said first aperture when said particle is within said
zone, wherein said contact surface and the set particle can be
spaced apart from said chamber;
means for changing the relative spacing between said set particle
and said chamber, so that when said contact surface is
substantially contacting said chamber, a partial boundary is formed
around said particle by said chamber and said contact surface;
means for transmitting said emitted radiation from the partially
bounded particle to said sensor;
a source of energy capable of heating said particle until a fluid
emanates from a portion of the partially bounded particle;
means for transferring energy from said energy source to a portion
of the partially bounded particle;
means for collecting said fluid from said chamber;
wherein said chamber also comprises an abutting end surface at or
near said first aperture;
wherein said radiation is visible light and said sensor is a
microscope having an objective lens;
wherein said chamber also comprises a first window located
substantially around said axis and attached to a second aperture,
wherein said first window is transparent to radiation within the
visible frequency band and said window is located at or near said
objective lens;
wherein said contact surface is a generally planar surface
perpendicular to said axis, wherein said contact surface is movably
mounted to said microscope, said contact surface capable of moving
in a directions perpendicular and parallel to said axis; and
wherein said source of energy comprises a controlled intensity and
duration laser beam source of a heating beam along a path from said
energy source to said particle wherein a portion of said path
diverts from said axis, said energy source capable of generating a
fluid pyrolyzate from said particle; and
wherein said means for transferring energy comprises:
a second chamber window attached to a third aperture of said
chamber which is separated from said first window, said second
chamber window located along the path of said heating beam and
wherein said second window is generally translucent to said heating
beam; and
means for directing said heating beam onto a portion of said
particle.
7. The apparatus of claim 6 wherein said second window is spaced
apart from said first window.
8. The apparatus of claim 6 wherein said source of energy produces
a near-infrared frequency heating laser beam directed towards said
second chamber window and said means for transferring energy also
comprises:
a digitally controlled shutter controlled by a controller and
located along the path of said heating laser beam, the shutter
limiting the passage of said heating beam when closed; and
wherein said means for directing comprises at least one mirror
adjusably mounted within said chamber.
9. The apparatus of claim 8 wherein said chamber has a threadable
attachment surface and said mirror is threadably attached to said
chamber.
10. The apparatus of claim 9 which also comprises:
means for chemically analyzing said collected pyrolyzate fluid
outside said chamber; and
means for transporting said collected pyrolyzate fluid to said
means for chemically analyzing.
11. The apparatus of claim 10 wherein said means for chemically
analyzing comprises a chromatographic analyzer device and a
spectrometer analyzer device, and said means for transporting
comprises a heated duct attached to said chamber.
12. The apparatus of claim 11 wherein said means for chemically
analyzing is connected to said means for transporting and said
means for chemically analyzing also comprises a means for
selectably controlling the transfer of said pyrolyzate fluid to
said analyzer devices.
13. The apparatus of claim 12 wherein said means for selectably
controlling comprises a 6-way valve.
14. The apparatus of claim 13 which also comprises:
means for evacuating the interior of said chamber attached to an
aperture of said chamber;
means for supplying inert gas to said interior attached to an
aperture of said chamber for purging the interior of said chamber
with inert gas; and
a source of inert gas connected to said means for supplying.
15. The apparatus of claim 14 which also comprises a targeting
laser source capable of producing a visible laser beam colinear
with said heating laser beam within said chamber.
16. The apparatus of claim 15 wherein said laser sources also
include a means for focusing said laser beams onto an area on a
planar surface of said sample, a portion of which is substantially
within said chamber, said area having a representative dimension as
small as 10 microns in diameter.
17. The apparatus of claim 15 wherein said contact surface is a
glass slide.
18. The apparatus of claim 17 wherein said sample is attached to
said glass slide by means of a putty-like material.
19. The apparatus of claim 18 wherein said sample is cast in an
encasing material which fully encloses said sample except for an
exposed surface, and said putty-like material is attached to a
surface of said encasing material distal from said exposed
surface.
20. The apparatus of claim 19 wherein said encasing material is a
clear acrylic plastic.
21. The apparatus of claim 15 wherein said at least a portion of
said contact surface not including said particle comprises a
polished surface of said sample.
22. An apparatus for use when analyzing a small particle within a
sample, said apparatus comprising:
an optical sensor having a focal plane, said sensor sensing said
small particles when located in a zone which includes said focal
plane;
a source of heat capable of heating said particle and generating a
fluid pyrolyzate from said particle when it is located
substantially in said focal plane;
a walled chamber only partially enclosing a cavity, said chamber
having an aperture in a first wall section, and a second wall
section located proximate to said optical sensor;
a relatively planar sealing surface for sealing said aperture
wherein said planar sealing surface is attachable to said
particle;
means for concurrently moving said sample and said planar sealing
surface to a position relative to said chamber, said position
substantially intersecting said axis and parallel to said focal
plane when said sealing surface is sealably abutting said aperture,
wherein said abutted chamber and said sealing surface form
unattached segments of an enclosed cavity;
means for transmitting heat from said heat source to a portion of
said particle, wherein said means for transmitting heat is separate
from said means for transmitting light; and
means for collecting said fluid pyrolyzate.
23. An apparatus for use when analyzing a small particle within a
composite sample having a sealing surface, said apparatus
comprising:
an optical sensor having a focal plane, said sensor sensing said
small particle when located within a zone which includes said focal
plane;
a source of heat capable of heating said particle and generating a
fluid pyrolyzate from said particle when it is located within said
zone;
a walled chamber partially enclosing a cavity, said chamber having
an apertured first wall section, and a second wall section located
proximate to said optical sensor;
means for locating said sealing surface and said sample within said
zone when said apertured wall section is abutting said sealing
surface, wherein said abutted chamber and said sealing surface form
unattached segments of a cavity generally enclosing said
particle;
means for transmitting light from said sealing surface to said
optical sensor; and
means for transmitting heat from said heat source to said
particle.
24. An apparatus for use when analyzing a small particle within a
composite sample, said apparatus comprising:
an optical sensor having a focal plane, said sensor sensing said
small particle when located within a zone which includes said focal
plane;
a source of heat capable of heating said particle and generating a
fluid pyrolyzate from said particle when said particle is located
within said zone;
a walled chamber partially enclosing a cavity, said chamber having
an apertured first wall section, and a second wall section located
proximate to said optical sensor;
a chamber sealing surface detachably connected to said sample, said
sealing surface located within a first specific distance from said
focal plane and within a second specific distance from one of the
surfaces of said sample;
means for transmitting light from said cavity to said optical
sensor;
means for sealably abutting said apertured first wall section to
said sealing surface, wherein said abutted chamber and said sealing
surface form unattached segments of an enclosed cavity wherein the
abutting motion changes the relative spacing between the sealing
surface and particle;
means for transmitting heat from said heat source to a portion of
said particle, wherein said means for transmitting energy is
separate from said means for transmitting light; and
means for collecting said fluid pyrolyzate.
25. A chamber apparatus for analyzing a particle within a composite
sample, said apparatus comprising:
a walled chamber capable of partially enclosing said particle;
a source of heat capable of generating a fluid pyrolyzate from said
particle when partially enclosed by said chamber;
an analyzer capable of detecting a property of said fluid
pyrolyzate;
a duct for passing said fluid pyrolyzate passing through an
aperture of said partial enclosure, a first portion of said duct
having a first end generally outside said partial enclosure, and a
second end of said first portion connected to said analyzer;
means for heating said first duct portion, wherein said means for
heating is capable of maintaining said first duct portion above a
first minimum temperature;
a second duct portion attached at one end to said first end of said
first duct portion, said second duct portion transporting said
fluid pyrolyzates from near said enclosed particle to said first
end of said first portion, wherein a said second duct portion is
composed of a thermally conductive material in thermal contact with
said means for heating;
means for thermally insulating said duct from said sample; wherein
said thermal insulating and heating means are capable of
maintaining said second duct portion above a second minimum
temperature sufficient to prevent a change of phase of said fluid
pyrolyzate within said second duct portion when said first duct
portion is at said first minimum temperature; and
means for transporting said fluid within said duct.
26. The apparatus of claim 25 wherein said means for transporting
comprises:
a source of inert gas;
a third duct portion connecting said inert gas
source to said chamber; and
means for moving said inert gas and said pyrolyzate fluid.
27. The apparatus of claim 26 wherein said third duct portion is
partially composed of an aluminum containing material.
28. The apparatus of claim 26 wherein said heating and thermal
insulating means are also capable of maintaining the temperature of
said chamber below a third temperature, when said chamber is cooled
by natural convention contact with ambient air.
29. The apparatus of claim 28 wherein the shape of said second duct
portion is capable of being deformed into a plurality of positions,
wherein at least one of said positions is capable of transporting a
portion of said pyrolyzate fluid to said analyzer when carried
along with said inert gas.
30. The apparatus of claim 29 wherein said second duct portion is
partially composed of a copper containing material.
31. The apparatus of claim 29 wherein said duct is partially
composed of brass.
32. The apparatus of claim 31 wherein said duct is composed of
exterior brass tube sections in concentric thermal contact with
interior tubes sections composed of a nickel containing
material.
33. The apparatus of claim 32 wherein said thermal insulating means
comprises a ceramic insulator material attached to one of said wall
sections and said insulating means is also capable of supporting
one of said tubes.
34. The apparatus of claim 33 wherein said ceramic insulating means
is capable of maintaining said second duct portion at said second
minimum temperature when the fluid and inert gas pressure within
said chamber is approximately one atmosphere.
35. The apparatus of claim 34 wherein said source of heat is a
directable laser beam capable of impingement upon a portion of said
enclosed particle.
36. The apparatus of claim 35 which also comprises a translucent
window attached to one of said walls in the path of said laser
beam, said window capable of transmitting said laser beam to the
interior of said chamber.
37. A chamber apparatus for analyzing one type of particle within a
composite sample having a plurality of particles of said one
particle type, said apparatus comprising:
first means for generating a first quantity of a fluid pyrolyzate
from a first portion of one of said plurality of particles of said
one particle type;
second means for generating a second quantity of said fluid
pyrolyzate from a second portion of one of said plurality of
particles of said one particle type;
a walled chamber capable of partially containing each of said fluid
pyrolyzate quantities;
means for collecting each of said fluid pyrolyzate quantities from
said chamber to outside said chamber;
means for trapping said collected quantities of pyrolyzate outside
said chamber;
a pyrolysis fluid analyzer connected to said means for trapping,
wherein said analyzer requires a minimum resolution amount of
fluid;
means for releasing trapped quantities of pyrolyzate in an amount
at least equal to said minimum resolution amount; and
means for transporting said released quantities to said
analyzer.
38. The apparatus of claim 37 which also comprises means for
supplying said chamber with an inert gas.
39. The apparatus of claim 38 which comprises a plurality of said
pyrolysis fluid analysis sensors within said pyrolysis fluid
analyzer to analyze the different quantities of pyrolysis
fluids.
40. The apparatus of claim 39 wherein said means for generating
comprises a laser beam energy source generating a laser beam having
a frequency which is partially absorbed by said particle portions
and wherein said absorbed energy is converted into heat.
41. The apparatus of claim 40 wherein the first of said sensors
comprises a gas chromatograph device and a second of said sensors
comprises a mass spectrometer, wherein a pyrolyzate fluid output of
said gas chromatograph is connected to an input of said mass
spectrometer device.
42. A chamber apparatus for analyzing one type of particle within a
composite sample having a plurality of particles of said one
particle type, said apparatus comprising:
first means for generating a first quantity of a fluid pyrolyzate
from a first portion of one of said plurality of particles of said
one particle type;
second means for generating a second quantity of said fluid
pyrolyzate from a second portion of one of said plurality of
particles of said one particle type;
a walled chamber capable of partially containing each of said fluid
pyrolyzate quantities;
means for collecting each of said fluid pyrolyzate quantities from
said chamber to outside said chamber;
means for trapping said collected quantities of pyrolyzate outside
said chamber;
a pyrolysis fluid analyzer connected to said means for trapping,
wherein said analyzer requires a minimum resolution amount of
fluid;
means for releasing trapped quantities of pyrolyzate in an amount
of at least equal to said minimum resolution amount;
means for transporting said released quantities to said
analyzer;
means for supplying said chamber with an inert gas;
a plurality of said pyrolysis fluid analysis sensors in said
pyrolysis fluid analyzer to analyze the different quantities of
pyrolysis fluids;
wherein said means for generating comprises a laser beam energy
source generating a laser beam having a frequency which is
partially absorbed by said particle portions and wherein said
absorbed energy is converted into heat;
wherein the first of said sensors comprises a gas chromatograph
device and a second of said sensors comprises a mass spectrometer,
wherein a pyrolyzate fluid output of said gas chromatograph is
connected to an input of said mass spectrometer device; and
wherein said means for trapping comprises a cold trap cooled by a
source of liquid nitrogen coolant, wherein said cold trap is
capable of condensing gaseous pyrolyzates.
43. The apparatus of claim 42 wherein said means for releasing
comprises:
means for controlling said coolant supplied to said cold trap;
and
means for heating said cold trap to a temperature capable of
vaporizing a portion of said condensed pyrolyzates.
44. The apparatus of claim 43 wherein said means for generating
procedures at least one of the fluid pyrolyzate quantities smaller
than said minimum resolution amount.
45. An apparatus for analyzing a particle within a composite sample
comprising:
a laser beam source generating a controlled duration heating laser
beam having a representative initial beam cross sectional dimension
at a first location, said beam capable of impinging on one surface
of said sample and generating a fluid pyrolyzate;
a walled chamber capable of partially containing said fluid
pyrolyzate;
a fluid pyrolyzate analysis sensor in fluid communication with said
chamber;
means for enlarging said initial heating beam dimension located
between said first location and said particle;
means for converging said enlarged heating beam dimension to
produce a focal spot located at or near a portion of said particle
and having a representative cross sectional spot dimension smaller
than said initial heating beam dimension; and
means for transporting said generated pyrolyzate from said walled
chamber to said sensor.
46. The apparatus of claim 45 which also comprises:
a targeting laser beam source for targeting said heating beam, said
targeting laser beam capable of generating a visible beam within
said chamber colinear with said heating beam; and
means for adjustably directing said visible beam and said
converging heating onto said particle.
47. The apparatus of claim 46 wherein said means for adjustably
directing is a multi-position mirror attached to said chamber.
48. The apparatus of claim 47 wherein said initial beam dimension
is a diameter no larger than 2 mm. and said means for converging is
an achromatic generally circularly shaped lens having a diameter of
at least 1.5 cm.
49. An apparatus for analyzing a particle within a sample having a
plurality of particles, said apparatus comprising:
a remote sensor capable of detecting radiation emitted from said
particle, said sensor having an axis around which detected
radiation is centered and having a zonal distance along a portion
of said axis wherein detection sensitivity of said sensor is nearly
maximum;
a walled chamber attached to said sensor and partially enclosing a
cavity, said chamber having a first aperture in a first wall
section located distal from said sensor and at or near said
axis;
a first aperture sealing surface attached to said particle, said
sealing surface shaped and dimensioned to mate with said first
aperture when said connected particle is at or near said axis and
within said zonal distance;
a means for moving said first aperture sealing surface in a
direction having a component generally parallel to said axis;
wherein said moving means is capable of sealably abutting said
first aperture to said sealing surface to form a generally enclosed
cavity;
a laser beam heat source producing a heating beam of controlled
duration and having a representative initial beam cross sectional
dimension, said beam capable of generating a plurality of fluid
quantities from said particle when within said enclosed cavity;
a targeting laser beam source generating a visible beam colinear
with said heating beam within said chamber;
means for enlarging said initial heating beam dimension;
means for converging said enlarged heating beam dimension, wherein
said means for converging is capable of producing a focal spot
within said chamber having a representative cross sectional spot
dimension smaller than said beam cross sectional dimension and said
focal spot is located at or near said zonal distance when said
particle is enclosed;
a beam window attached to a wall section of said chamber, and
located in the path of said converging heating beam when said
particle is enclosed;
means for adjustably directing said visible beam and said focal
spot onto said particle;
a first chromatographic analyzer of said fluid;
a second mass spectroscopic analyzer of said fluid;
a duct for transporting said fluid to said analyzers, said duct
comprising a first portion duct having a first end at or near one
of said wall sections and a second end in fluid communication with
said analyzers;
means for heating said first duct, wherein said means for heating
is capable of maintaining said first duct portion above a first
minimum temperature;
a second duct portion for transporting said fluid from near said
particle within said chamber to said first end of said first duct
portion, wherein said second duct portion is partially composed of
a thermally conductive material and is in thermal contact with said
first duct means;
means for supporting and thermally insulating said ducts from said
walled chamber; wherein said insulating means is capable of
maintaining said second duct above a second minimum temperature
sufficient to prevent a change of phase of said fluid within said
second duct when transporting said fluid and when said first duct
is at said first temperature; means for trapping said generated
quantities of gaseous fluid; and
means for releasing said trapped quantities of gaseous fluid to
said analyzers, wherein said released amount is at least equal to
said minimum resolution amount.
50. The apparatus of claim 49 wherein:
said remote sensor is a microscope and said detected radiation is
visible light;
said means for moving comprises a microscope stage translating
mechanism;
said laser beam source produces a laser beam within the
near-infrared, middle-infrared and far-infrared frequency
ranges;
said means for enlarging and said means for converging said heating
beam comprise lenses placed in the path of said laser beam;
said means for adjustable directing comprises a mirror threadably
attached to said chamber;
said means for supporting and thermally insulating comprising a
ceramic insulator material connecting said chamber and one of said
ducts;
said means for trapping comprises a cold trap and a source of
coolant; and
said means for releasing comprises a control valved connection of
said coolant to said cold trap, and means for heating said cold
trap.
51. A chamber apparatus for analyzing a particle within a composite
sample, said apparatus comprising:
a chamber for at least partially enclosing said sample;
means for moving of said sample to contact a portion of said
chamber, at least a portion of said sample located within said
chamber when in contact;
a source of heat capable of generating a fluid pyrolyzate from said
particle when said sample is in contact with said chamber, wherein
said chamber is capable of partially enclosing said fluid
pyrolyzate;
an analyzer capable of detecting a property of said fluid
pyrolyzate when said fluid pyrolyzate is transported to said
analyzer;
a thermally conductive duct for transporting said fluid pyrolyzate
from said camber to said analyzer, wherein said duct is comprised
of a first duct portion having a first end outside said partial
enclosure, and a second end in fluid communication with said
analyzer;
means for reducing the temperature of said first duct portion until
said first duct portion is below a first maximum temperature;
a second duct portion for trapping said partially enclosed fluid
pyrolyzate, said second duct portion extending from near said
particle to said first end of said first duct portion; and
means for thermally insulating said duct from said sample; wherein
said thermal insulating and said reducing means are capable of
maintaining said second duct portion below a second maximum
temperature sufficient to change the phase of said fluid pyrolyzate
within said second duct portion when said first duct portion is at
said first maximum temperature.
52. An apparatus for analyzing a particle within a sample, said
apparatus comprising:
a sensor capable of detecting radiation issuing from said particle,
said sensor detecting radiation centered around an axis and having
a focal zone located so that it includes a focal distance along a
portion of said axis wherein detection sensitivity of said sensor
within said focal zone is substantially at a maximum;
a source of a heating laser beam capable of heating and generating
a fluid from a portion of said particle;
a chamber extended along a portion of said axis and partially
enclosing a cavity and attached to said sensor, said chamber
comprising:
a fluid impermeable wall composed of materials transparent to said
issued radiation and said heating laser beam;
a touch surface attached to said chamber for contacting a contact
surface; and
a first chamber aperture near said touch surface, located in said
wall substantially around said axis;
a contact member for more fully enclosing said chamber and spaced
apart from said particle, said contact member having a contact
surface shaped and dimensioned to contact said touch surface when
said spaced apart particle is at or near said focal zone;
a means for concurrently moving said contact member and said spaced
apart particle towards said touch surface until said contact member
reaches said contact surface forming a partial boundary around said
fluid generated by said heating laser beam; and
means for collecting said fluid from said chamber.
53. The apparatus of claim 52 wherein said chamber is a duct-like
shape having a first duct end and a second duct end connected to
said means for collecting, wherein said first chamber aperture is
located nearly equidistant from said first and second duct
ends.
54. The apparatus of claim 53 which also comprises:
means for supplying inert gas to said first duct end; and
a source of inert gas connected to said means for supplying.
55. The apparatus of claim 54 said duct-like chamber is shaped and
dimensioned to sweep said inert gas across said first chamber
aperture to said means for collecting.
56. The apparatus of claim 55 wherein said duct-like chamber is
tubular having a fluid flow deviation form located at or near said
first chamber aperture.
57. The apparatus of claim 55 wherein said chamber is composed of
clear quartz.
58. The apparatus of claim 57 wherein said means for collecting is
a tube thermally insulated from and attached to said chamber.
59. The apparatus of claim 55 wherein said touch comprises an
abutting portion of said duct-like chamber, wherein said abutting
portion is shaped and dimensioned to form a generally gas tight
seal.
60. An apparatus for analyzing a particle within a sample having a
plurality of particles, said apparatus comprising:
a remote sensor capable of detecting radiation emitted from said
particle, said sensor having an axis around which detected
radiation is centered and having a zone along a portion of said
axis wherein detection sensitivity of said sensor is nearly
maximum;
a walled chamber attached to said sensor and partially enclosing a
cavity extending along said axis and having an aperture in a wall
section located distal from said sensor;
a support member for supporting said particle at a distance from
said sensor, said support member having an aperture sealing surface
shaped and dimensioned to mate with said aperture when said
particle is supported within said zone, wherein said mated support
member and chamber forms a substantially enclosed cavity around
said particle;
a means for changing said distance wherein said changing means
concurrently changes the distance between said aperture and said
sealing surface.
61. The apparatus of claim 60 which also comprises:
a laser beam heat source producing a heating beam capable of being
transmitted into said cavity and generating a fluid quantity from
said particle within said enclosed cavity; and
means for chemically analyzing said fluid quantity.
62. An apparatus for analyzing a particle within a sample, said
apparatus comprising:
a sensor capable of detecting emitted radiation from said particle
within a detection zone, said sensor detecting emitted radiation
centered around an axis and said zone located substantially around
a portion of said axis wherein detection sensitivity of said sensor
is substantially at a maximum sensitivity from within said
zone;
a chamber attached to said sensor wherein at least a portion of
said chamber extends along said axis towards said particle, said
chamber having a first chamber aperture located substantially
around said axis;
a contact surface for setting said particle, at least a portion of
said contact surface spaced apart from said particle, said contact
surface shaped and dimensioned to seal the first aperture of said
chamber when said particle is within said zone, wherein said
contact surface and the set particle can be spaced apart from said
chamber;
means for changing the relative spacing between said set particle
and said chamber so that when said contact surface is substantially
contacting said chamber, a partial boundary is formed around said
particle by said chamber and said contact surface.
63. The apparatus of claim 62 which also comprises:
means for transmitting said emitted radiation from the partially
bounded particle to said sensor;
a source of energy capable of heating said particle until a fluid
emanates from a portion of the partially bounded particle;
means for transferring energy from said energy source to a portion
of the partially bounded particle; and
wherein said source of energy comprises a controlled intensity and
duration laser beam source of a heating beam along a path from said
energy source to said particle, said energy source capable of
generating a fluid pyrolyzate from said particle.
Description
FIELD OF THE INVENTION
This invention relates to the analysis by microscope and analysis
by thermal extraction or pyrolysis of samples composed of
microscopic particles. More specifically, the invention relates to
devices and methods for the combined optical and thermal analysis
of geological or other composite samples composed of different
types of pyrolyzable microscopic particles.
BACKGROUND OF THE INVENTION
Many geological, biological, man-made and other solid materials are
heterogeneous composite structures formed from interrelated, but
microscopically and chemically discrete entities, such as particles
or cells. If an analysis of the chemical or physical properties of
this type of composite sample is desired, the analysis method and
device must address these various microscopic entities. The primary
objectives of an analysis of the properties of these composite
samples are to: 1) locate and identify the physical structure of
each type of particle within one sample; 2) identify the chemical
or other properties of that particle type; 3) identify the physical
relationships among the various particle types within the sample;
and 4) be capable of analyzing a wide variety of particle types.
The analyzer device should also be light weight, rugged in
construction, low in cost, and easy to operate. The process using
the analyzer should also be capable of several active analyzing and
storage modes. These include: an on-line analysis mode, an off-line
analysis mode, a temporary rest mode, and a long term storage mode.
A minimum of effort to convert from one mode to another is also
desirable.
Most of the current analyzers may accomplish some of these
objectives well, but other objectives are accomplished poorly or
not at all. A common analysis technique involves splitting the
sample. A small sample portion is prepared for optical analysis
(microscopic examination), while a second portion is prepared for a
separate bulk chemical analysis, for example bulk analysis by
pyrolysis. This two step process, however tends to be slow,
complex, and unreliable. In addition, the bulk analysis step
obscures the chemical properties of each particle as well as the
relationships among the particles which comprise the composite
sample, i.e., a sample composed of diverse particles. The bulk
chemical analysis yields information from all particles producing
significant pyrolyzates within the sample. It may not be possible
to reconstruct the contribution(s) of each type of particle from
the mixed particle pyrolyzate information generated by this bulk
analysis approach.
The bulk analysis process step typically requires crushing, placing
the crushed sample in an enclosed container, heating the crushed
sample to elevated temperatures which generates a pyrolyzate fluid,
and transporting the fluid to a chemical "bulk analysis" device.
The enclosed container and heating device may also be part of the
"bulk analysis" device. The chemical "bulk analysis" device may be
a gas-liquid chromatograph, or a mass spectrometer or a nuclear
resonance spectrometer. An example of devices used for this
pyrolysis analysis method, without any means for optical viewing,
can be found in U.S. Pat. No. 4,408,125.
This "bulk" method generates measurable quantities of pyrolyzates
from groups of microscopic particles within a composite sample
which individually could not generate sufficient pyrolyzates for
chemical analysis. The bulk pyrolysis process can also be applied
to large individual or groups of similar particles separated from
the composite sample. However, physical or chemical separation of
microscopic particles prior to pyrolysis is difficult, e.g.,
density gradient centrifugation. Furthermore, separation can alter
the chemical and physical properties of the microscopic particles
and destroy the relationships among these particles.
As an alternative to ordinary heating (pyrolysis or thermal
extraction) sources, a laser beam can be used as a source of
thermal energy or heating. This is illustrated in U.S. Pat. Nos.
4,025,790 and 4,672,169. The processes described in these patents
are for gases, not particles. The laser selectively excites (i.e.,
the laser beam's infrared energy is absorbed by) certain gaseous
compounds in a mixed sample within an enclosed chamber. Laser beam
heating has several advantages. It allows for directing heat into a
specific zone and rapidly heating (i.e., more quickly heating than
conventional sources of heat) the specific gaseous compounds of
interest.
The separate microscopic and thermal extraction or pyrolysis bulk
analysis approach requires sample transport between the microscopic
examination and the heating/pyrolyzate analyzer devices. The
multi-step approach also tends to limit the speed and use of
devices in this sequential step type of analysis. One can also
never be sure that the spit sample portions are identical for
composite samples. Reconstruction of each type of pyrolyzate
producing particle present in the composite sample from the bulk
information produced, even if possible, can also be unreliable.
An integrated optical and pyrolysis approach is also known. One
integrated approach modifies a laser heating pyrolysis system by
adding a microscope. The sample is placed in a pyrolysis chamber
which includes a window for microscopic examination and laser beam
transmission. In addition, other equipment may be required to allow
optical focusing, illumination, and sample viewing placement,
removal, and manipulation.
The optical modifications to the basic pyrolysis chamber design
compromise the performance of both the optical and pyrolysis
analysis systems. For example, the combined device must: 1)
accommodate the transmission of the narrow laser beam and the
microscope's broader light beam or field of view; 2) allow for the
proper sample focusing of the laser beam and optical microscope
systems; 3) allow sufficient space between the sample and the
window to avoid window clouding and overheating from contact with
the hot pyrolyzates, but be close enough to avoid changing the
focal lengths of each system; and 4) provide a chamber large enough
to include the added components but not so large as to dilute or
ineffectually collect the small quantities of pyrolyzates which may
be produced. In addition, the multiplicity of elements required to
accomplish both analyses tends to get in the way of each other in
the confined space of a pyrolysis chamber. This further limits
operational use, reliability and flexibility. These problems also
tend to limit the combined analysis device to specific sample sizes
and particle types.
A second method, which is the inverse of this first integrated
approach (modifying a pyrolysis system), converts an optical system
(microscope). The optical system is modified to include a colinear
heating laser beam and an open sided chamber. The open side of the
chamber is placed on a conventional glass slide on the microscope
stage. The remainder of the system includes a chamber window, a
supply of a purge gas, and a collection tube. This second or
inverse integrated approach is illustrated in U.S. Pat. No.
3,941,567. However, this inverse approach also requires design
compromises similar to the first integrated approach.
A specific sample of the integrated approach design comprises and
problems occurs if analysis of a single type of particle within a
composite sample is desired. Focusing of the pyrolyzing laser beam
requires a narrow beam, smaller than the representative dimension
of the particle. The laser beam or particle location must also be
adjustable, so that the beam may be pointed or aimed at the spot on
the particle of interest. The adjustment may also require
refocusing of both the microscope and laser systems. Very small
individual particles may not be capable of generating sufficient
pyrolyzate upon laser beam heating to be detected by an analyzer,
even if the beam is narrow and properly focused. These problems may
limit the application of this combined laser and microscope system
to only larger particles within the composite sample.
The collection of the hot gaseous pyrolyzate fluids also presents
problems. Hot pyrolyzate gases tend to condense on any cooler
(i.e., ambient) temperature surfaces of the chamber. Heating the
chamber may prevent condensation, but can lead to optical
distortions, thermal expansion, seal failures, and outgassing of
chamber materials, and pyrolysis of other particles (causing bulk
release and contamination of the analysis).
SUMMARY OF THE INVENTION
A simple apparatus and method capable of determining properties of
very small individual particles in composite samples is needed to
overcome the limitations of the prior art. The method should also
minimize complex sample preparation, sample inserting and
positioning, chamber enclosing/sealing, separate focusing, heating
errors, and post-pyrolysis reconstruction of multi-pyrolyzate bulk
information.
These and other needs are met by a method of using an integrated
laser heating and microscope apparatus including a shaped chamber
attached to a microscope, the chamber having an opening at its
lower side and a thermally insulated and conductively heated
gaseous pyrolyzate collection tube. The chamber is transparent to
visible and laser heating beam transmissions, and the insulated
collection tube is conductively heated to prevent pyrolyzate
condensation. A composite sample surface (containing one or more
particles of interest on an exposed surface) serves to seal the
chamber opening when it is raised toward the opening of the
chamber. Raising the sample on the microscope stage both encloses
the sample surface and brings the particle into the common focal
plane of both the microscope and laser systems. Using incident
light illumination, a small spot on the particle of interest is
selected (by observation through the microscope) and centered
within the field of vision.
A heating laser beam diameter is first expanded to be conveniently
converged and focused directly onto the diffraction-limited spot on
the particle of interest. The beam expansion and converging process
and impact generates a small quantity of pyrolyzate gases from a
single pre-selected particle spot. After the spot heating, the
small quantity of effluent pyrolyzate gas is both sucked and swept
(by an inert gas supply flow within the shaped chamber) into a
conductively heated tube which carries the gases to a cold trap,
where condensed hot pyrolyzate gases are retained. Additional
heating bursts by the laser beam at different spots on the particle
or other microscopically identical particles of the same type,
generates added pyrolyzate gas quantities which are collectively
stored in the cold trap. Collection and storage continue until a
sufficient quantity for analysis is retained in the cold trap.
Warming the cold trap vaporizes the stored multi-burst pyrolyzate
gas quantities, which are then sequentially analyzed by a gas
chromatograph and a mass spectrometer.
The multi-burst process, small spot focusing, collection tube
placement and insulation, and transparent chamber shape allow quick
optical and thermal extraction or pyrolysis analysis of a particle
within a composite sample previously too small for combined
analysis. The apparatus also permits both a microscopic and
chemical analysis on the same exact particle and avoids previous
design compromises and problems.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a schematic of a combined microscope and pyrolysis
analysis system;
FIG. 2 shows a front schematic cross sectional view of a first
alternative sample chamber portion of the analysis system;
FIG. 3 shows a schematic front cross sectional view of a second
alternative sample chamber;
FIG. 4 shows a schematic side cross sectional view of the sample
chamber shown in FIG. 3;
FIG. 5 shows a perspective cut-away view of the sample chamber
shown in FIG. 3;
FIG. 6 shows a perspective side view of the preferred embodiment of
the sample chamber portion of the apparatus; and
FIG. 7 shows a cross sectional view of the preferred embodiment
sample chamber.
Like numerals refer to like elements.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 is a schematic representation of an optical and thermal
extraction or pyrolysis analysis system for analyzing a particle
within a composite sample. A first or optical laser source 2
provides a low power visible beam of light 3 to a fixed mirror 4.
The diameter of beam 3 at the source is typically less than 2 mm.
and is approximately 0.6 mm. in the preferred embodiment. The
optical laser source 2 in the preferred embodiment is provided by a
red Helium-Neon laser having a wavelength of 632.8 nanometers, but
any laser device for generating a low intensity (typically less
than 0.01 watt) beam of electromagnetic radiation within the
visible spectrum is acceptable. The visible laser beam 3 targets a
second near-infrared (and not visible) laser beam from heating
energy source 5.
The second or near-infrared or heating laser beam source 5 produces
an infrared or near-infrared laser beam 6 directed to an electronic
shutter 7. The near-infrared laser source 5 in the preferred
embodiment is provided by a 5 W continuous wave Nd:YAG laser, but
any device for generating sufficient energy or heat can be used.
The laser output is polarized and the laser source is operated in a
multi-mode rather than a single mode to obtain full power
capability. The laser source 5 must generate a laser beam of
electromagnetic radiation within a frequency band which is a)
absorbed by (i.e., heats) a particle within a composite sample 32
(see FIG. 2), and b) of sufficient intensity to generate a thermal
extraction or pyrolyzate fluid. Laser frequencies are expected to
be within the near-infrared, middle-infrared and far infrared
bands, i.e., wavelength of between 0.75 to 1000 microns). In
addition to the preferred near-infrared laser source 5, other
embodiments may employ alternative or added sources of heat and
absorbed energy, such as additional heating laser beams or contact
filament heaters.
Whether the laser beam from infrared source 5 passes through
shutter 7 is governed by shutter control device 8. Shutter control
is preferably accomplished by a digital programmable function set
to open the shutter for a selected time period ranging from 10 to
990,000 milliseconds. Selection of the shutter opening time can be
based upon observed particle material, particle size, particle
shape, and the amount of pyrolyzate desired. Shorter or longer
digital or manual shutter control times are also possible in other
embodiments. Shutter control 8 may also be a chopper, allowing a
series of repeated pulses of the near-infrared laser beam 6 to be
transmitted to the beam splitter 9.
The beam splitter 9 is a dichroic mirror. The dichroic mirror can
coaxially combine the visible beam 3 reflected from fixed mirror 4
and transmit the near-infrared beam 6 to a variable attenuator 10.
The attenuator 10 contains a prism and waveplate. These attenuate
the polarized output of the Nd:YAG laser source 5 as the waveplate
rotates in a plane perpendicular to the incoming beams. A polarized
lens can also be used to attenuate the intensity of the laser beam.
Attenuation control (not shown for clarity) can be by manual or
device driven rotation of the attenuator 10. This selectably allows
a full attenuation range from 0% to 100% of the near-infrared laser
beam's energy to be transmitted to a diverging input lens 11.
"Diverging" input lens 11 in the preferred embodiment is actually a
converging lens in which the beam is converged to a focal spot
after which the beam diverges. The converging lens 12 is placed at
a divergent beam location, i.e., past the focal point.
In order to focus the near-infrared 6 and visible beams 3 onto a
very small (approximately 10 micron diameter), diffraction limited
spot on the composite sample 32 (see FIG. 2), conventional (2 mm.
cross sectional beam diameter) laser beam sources must be even
further reduced. Instead of directly converging the 2 mm. laser
beam over the distance between converging lens 13 and the sample
surface (requiring very small or specialized components), the beam
diameter is first expanded in the diverging input lens 11 to more
conventional dimensions, then collimating the expanded beam in a
converging output lens 12 before finally converging the beam to a
focal point or spot. A final converging achromatic lens 13 narrowly
focuses the expanded and collimated beam(s) onto a spot within both
the microscope's optical field of view and the focal zone in the
sample chamber 14. This initial diverging-collimating converging
lens arrangement allows the achromatic converging lens 13 to have a
diameter ranging from 1.5 to 4.0 cm. Focal length of the converging
lens 13 is between 70 and 80 mm. in the preferred embodiment to
allow coincidence at the microscope focal plane (at the sample
surface). Without this initial diverging and collimating lens
arrangement, attaining a diffraction-limited point or spot size of
10 microns on the sample surface would not be possible.
The sample chamber assembly 14 includes a container 15 attached to
the objective lens portion of an incident light microscope 16. The
container 15 can have a variety of shapes and sizes, but all
containers partially enclose a cavity 17 and have a bottom opening
near the optical axis "a." Chamber shape and size allows
accomplishing two objectives in a single step. Covering the bottom
opening both seals the chamber and locates the sample surface (see
FIG. 2) containing the particle of interest within the cavity 17
and at the microscope's focal plane or zone (zone of maximum
sensitivity or focus). The focal zone is along the optical axis
"a," around which an optical field of view of the sample can be
detected by an observer. In other configurations, the microscope 16
may be any sensor of radiation emanating from a sample to be
analyzed.
The container 15 shown in FIG. 1 includes a first optical window 30
and a second laser window 38 (see FIG. 2) to allow microscopic
examination and the visible and near-infrared laser beams to enter
the cavity 17 partially enclosed by the container 15. The
microscope 16 includes a 50.times. (magnification power)
long-working distance air objective lens located proximate to the
sample chamber 14 and a 12.5.times. eye piece lens to provide
625.times.. However, the magnification power may be modified in
other embodiments by replacement of the objective or eye piece
lenses, if the focal length is consistent with the chamber and
sample placement.
The microscope 16 can view a variety of particles on one surface of
the composite sample. The viewer can identify a particle of
interest on an exposed surface of the prepared sample located
within the cavity 17 (see FIG. 2). The particle of interest in a
sample surface is located near the optical axis (center of the
field of view of detectable light) and within the focal plane or
maximum sensitivity zone of the microscope 16. An adjustable mirror
39 (see FIG. 2) points the visible (red) laser beam 3 onto the spot
on the particle of interest. The near-infrared laser beam 6,
controlled by shutter 7, intensively and instantaneously heats
and/or pyrolyzes a portion of the desired particle. The laser
heating generates a plume of gaseous or liquid effluents (fluid
pyrolyzates) into the cavity 17.
The specific container 15 shown in FIG. 1 also includes a port for
transmission of a purge or inert gas piping 18 to the cavity 17
from a supply or source of inert gas 19. In the preferred
embodiment, helium and a helium tank is the inert gas and the inert
gas source 19, respectively, but other purge or inert gases and
sources may be used. The helium gas purges the cavity of air and
contaminating gases before pyrolysis and acts as an inert gas
carrier for the small quantities of pyrolyzates generated from the
small spot on the particle of interest by the near-infrared laser
beam.
The container 15 also includes a port for a collection piping
system 20. An electrical resistance heater 21 heats portions of the
collection piping system external of the container 15 to a minimum
temperature controlled by temperature controller 22. The minimum
temperature of the piping system 20 must be sufficient to prevent
the condensation (or other change of phase) of the hot pyrolyzate
gases. Ceramic insulation 44 (see FIG. 4) thermally insulates the
portion of the cavity protruding collection piping from the cooler
(unheated) components of container 15. Ambient air natural
convection cools the outside of container 15.
Alternative embodiments may allow for cooling the outside of
container 15 (and associated components in thermal contact with the
container) by forced convection or placement of the container 15 in
a temperature controlled environment. Still other alternative
embodiments may provide for heating or cooling the entire chamber,
or insulate only a window or heat sensitive portions of the
apparatus. These other alternative embodiments allow more extensive
chamber heating or cooling, further minimizing condensation loss of
pyrolyzate gas on cool chamber components.
The cavity protruding portion of the collection piping system 20 is
heated by conduction to a minimum temperature which avoids
condensation of the hot pyrolyzate gases. Because of thermal
inefficiencies or insulation losses, the external piping portion is
at a slightly higher temperature than the temperature of the cavity
protruding portion of the piping system 20.
The collection piping system 20 can be used to first evacuate the
cavity 17 by a vacuum pump 23 prior to or in place of inert gas
purging. After purging, the vacuum pump 23 can remove excess purge
gas from inert gas piping 18. After heating and pyrolysis of a
portion of the microscopic particle enclosed by container 15, the
collection piping 20 collects the effluent pyrolyzate gases for
analysis. Control of vacuum, purge and gas collection is
accomplished by a manual valve 24a and a cold trap 24b. Manual
valve 24a in the preferred embodiment is a six way
manually-actuated valve, but may be one or more solenoid valves
controlled by an electronically programmed gas controller in other
embodiments.
A source of liquid nitrogen (not shown for clarity) cools cold trap
24b to quickly condense and retain (trap) all the pyrolyzate gas
while passing the inert (low condensation temperature)
purge/carrier gas. The cold trap can be used to combine multiple
quantities of pyrolyzate each time the shutter 7 and near-infrared
laser 6 (see FIG. 1) produces thermally generated extracts or hot
gaseous pyrolyzates. Each quantity of pyrolyzate or thermal extract
gases emitted from each burst or shuttered exposure may not be
sufficient to perform an analysis by an analyzer device, i.e, the
quantity may be below the minimum resolution amount needed by an
analysis device. After collecting a sufficient quantity of gases
for analysis, the cold trap warms by isolating the coolant source
and natural convection contact with the ambient air (and possible
heating from the analyzer device), vaporizing and releasing the
trapped pyrolyzates.
In alternative embodiments, one or more cold traps may be at other
locations along the piping collection system 20. One cold trap may
be placed close to the container 15, minimizing the length of
tubing which must be heated during pyrolysis. In another
embodiment, the cold trap could be placed adjacent to the chamber,
cooling (by conduction) the collection piping portion protruding
into the chamber. This alternative embodiment avoids the need to
heat the collection piping system altogether. The conductively
cooled protruding tube acts as part of the attached cold trap,
condensing the pyrolyzate as it emanates from the sample surface.
Multiple trapped pyrolyzate quantities may again be later vaporized
for mass spectrometric or other analysis. If the trap is
transported while cold (at below pyrolyzate condensation
temperatures), analysis can be accomplished off-line at a different
location.
The protruding and insulated collection piping portion 25 (see
FIGS. 1 and 4) of the collection piping system within cavity 17 has
one end located proximate to the sample surface containing the
particle of interest (i.e., the particle to be analyzed). The shape
and dimensions of inert gas supply piping 18 and the protruding
portion 25 tend to suck and sweep gases from the pyrolyzate plume
and face of the sample near the particle of interest. The
protruding portion can also be deformably adjusted to optimize
pyrolyzate sweep efficiency at different points of the sample
surface. Alternative embodiments would include multi-port or
multi-position protruding tubes as well as variously shaped nozzles
and tubes.
Analysis of the pyrolyzate collected in the collection piping
system 20 may be on-line (real time analysis with a warm cold trap
24b) or off-line (gas collected in cold trap 24b, and analyzed at a
later time). The control valve 24a can divert the collected
pyrolyzate directly (on-line mode) to a first chemical analysis
device 26. In the preferred embodiment, the first pyrolyzate
analysis device is a gas chromatograph, but other chemical analysis
devices or methods can also be used. The increasing temperature in
the internal heat source or oven of the gas chromatogragh heats and
volatilizes a stream of the "lighter" (i.e., low boiling point) gas
components of the trapped pyrolyzate gases. "Heavier" (i.e, higher
boiling point generally having higher molecular weight) components
are then produced as the temperature increases. The individual
components of the pyrolyzate (and inert carrier) gas stream are
chromatographically separated and are then transferred by a
transfer section 27, to a second pyrolyzate chemical analysis
device 28. The gas chromatograph and transfer section 27 must also
be heated to avoid pyrolyzate condensation. The second chemical
pyrolyzate fluid analysis device 28 in the preferred embodiment is
a mass selective detector or mass spectrometer, but other chemical
or other property detection and analysis devices can also be used.
Data system 29 collects and stores data from one or both pyrolyzate
analysis devices for display, evaluation, and analysis.
Optical window 30 transmits visible frequency electromagnetic
radiation (light) from the sample within cavity 17. The emitted
light from the particle is seen by a viewer observing the sample
through microscope 16. The microscope field of view at the focal
plane encompasses more than one particle within the sample in order
to select the microscopic particle of interest 49 (see FIG. 7).
FIG. 2 is a front schematic cross sectional view of a first
alternative embodiment of a sample chamber 14a. The open side of
container 15a is sealed in a fluid tight arrangement against the
polished surface of an encasement 31 of sample 32. The shape and
dimensions of container 15a again place a polished surface 34 of
the sample 32 and sample encasement 31 at the focal plane of
microscope 16 when container 15a abuts against the polished surface
34. The encasement 31 of the sample 32 is composed of a
cast-in-place, transparent acrylic plastic. Grinding one of the
surfaces 34 of sample 32 exposes and polishes a planar surface.
Other encasement or potting materials can also be used in other
embodiments to support and orient the sample from the microscope
stage 35 (see FIG. 1) and/or glass slide 35a (see FIG. 2). The
sample 32 can also be cut or sliced from a larger sample before
casting or encasing within the plastic to form the encased sample.
Normal microscope illumination (either from above or below the
sample) is sufficient without any added illumination when the
encasing material is translucent.
The polished surface 34 of the encased sample 31 provides a sealing
surface for an end seal 33. The end seal 33 is an O-ring attached
to the container 15. The O-ring generally defines the container
opening or aperture. In the embodiment shown, the O-ring is
composed of neoprene. Different shapes or O-rings composed of
Teflon, Viton or other elastomeric compounds may also be used.
The apertured container 15a is attached to the microscope 16 (shown
in part in FIG. 2) while the glass slide positions the attached
spaced-apart particle in sample 32. The glass slide 35a is
supported by the microscope stage 35 (see FIG. 1). The sample stage
can be raised or lowered to bring the polished sealing surface 34
of the encased sample 31 into focus, as observed through the
microscope 16. Height or distance "b" is selected to be
approximately equal to the focal length of the objective lens
located in the lens barrel of the microscope 16 near the sample 32.
The height or distance "b" from the sample surface 34 (including
the particle of interest) to the lens barrel is 1.25 cm for the
lens configuration described.
Adjustment of the microscope focus moves the microscope's sample
platform or microscope stage 35 along direction "a" (see FIG. 1).
Adjustment is capable of abutting the end seal 33 against the
polished sample and plastic surface 34 to effect an enclosure and
sealing of cavity 17. One movement (up and down direction "a") of
the stage 35 is typically accomplished by a knurled focus
adjustment knob and mechanism (not shown for clarity) of the
microscope 16. After end seal 33 abutably contacts the sealing
surface to form a generally sealed cavity 17a, the sealed cavity
can be purged of ambient air with helium, evacuated or pressurized.
Chamber 15a is attached to the lens barrel of microscope 16 by an
attach member 43 (see FIG. 4).
Optically viewing the sample through the microscope 16 (shown as
dashed lines "c" on FIG. 2 emanating from a field of view on the
polished surface of sample 32 and reaching the microscope 16) is
accomplished through optical window 30. The field of view in the
focal plane on surface 34 of the sample 32 encompasses many
microscopic particles. The microscope observer selects one spot or
portion of a single particle for near-infrared laser beam
pyrolysis. In the embodiment shown, the optical window 30 is
composed of BK7 quartz glass, having a diameter of approximately
1.5 cm and a thickness of approximately 0.25 cm. These window
dimensions and material provides maximum visibility and structural
strength to withstand the vacuum or pressure within the cavity 17a.
The light source (not shown for clarity) for illuminating the field
of view may be a variety of sources currently available for
microscope illumination.
The source of light may be placed above the cavity 17 illuminating
through the window 30 and emitted back (reflected) as light from
the polished surface 34. The source of the light may also be placed
below the sample 32, transmitting light through a transparent
encasing or potting plastic and thin (translucent) sample 32. In
other embodiments, a source of light may be placed within the
cavity 17a, if required. Proximate to the truncated cone of light
"c" from the field of view of the microscope 16 is one end of the
purge gas piping 18.
The encased sample 31 is adjustably mounted in putt 36 directly on
the microscope sample stage 35 (see FIG. 1), or glass slide 35a
supported by sample stage 35. Putty-like or clay material 36 is
placed between the bottom surface 37 of the encased sample 31 and
the microscope sample stage 35 or glass slide 35a. Compressing the
clay 36 between the encased sample 31 and glass slide 35a forms an
adjustable and removable position support and attachment. The
direction and amount of pressing place and orient the polished
surface 34. This location provides for optimum viewing and
pyrolysis within the focal plane of the microscope 16 and at the
small focal spot formed by the converging laser beam(s).
The pressing of the clay 36 is done in a conventional hand press
tool, having a stop fixture (not shown for clarity). The stop
fixture surface orients the pressed surface to a height within the
common microscope and laser beam focal planes/spots, and prevents
further pressing of the sample onto the glass slide 35a. A set-off
spacing ring surrounding the sample in the press can serve as the
stop fixture (not shown). The spacing ring assures a set-off
spacing and parallel alignment of surface 34 within the field of
view of the microscope concurrent with chamber sealing.
Mounting of the sample on the glass slide 35a also allows lateral
motion of the particle within the focal plane. This is accomplished
by lateral motion of the glass slide 35a (and attached sample) on
the parallel microscope stage below the glass slide 35a (see FIG.
1). This lateral motion can be accomplished by hand or by
mechanical clips and adjustment means (not shown for clarity)
commonly provided on microscope sample platforms or stages.
Mechanical means of lateral motion adjustment allows precise
placement under higher power magnification.
The laser beam (shown as dotted lines "d" in FIG. 2) emanating from
either laser source (shown in FIG. 1) passes through the second or
laser window 38. The laser window shown is composed of ZnSe, having
a diameter of 0.6 cm and a thickness of 0.3 cm. This material and
the dimensions maximize the amount of laser beam radiation
transmitted and the ability to withstand the heat and expected
vacuum or pressure cavity conditions. Alternative laser window
materials of construction, such as sapphire, may also be used. The
diameter of the laser window 30 is small compared to the optical
window because the converging laser beam diameter is small. The
converging beam diameter also minimizes the required size of the
laser mirror 39. The entire chamber may also be made of a
transparent material, eliminating the need for separate
windows.
The adjustably mounted laser mirror 39 allow the user to direct the
beam to the center of the field of view or to point the laser beam
upon different spots on the selected particle within the sample 32
while maintaining the focus. The laser mirror 39 is preferably
composed of glass, internally coated with silver, but may also be
gold- or aluminum-coated glass or plastic. The adjustably mounted
mirror is at approximately a 22.5 degree angle to the incident
laser beam "d" and threadably moves the mirror along the inclined
axis using threaded shaft 40. Alternative embodiments can include
non-planar mirrors, alternative angles or a plurality of adjustable
mirrors for flexible and precise location and direction of laser
beam impingements on the selected spot.
The threaded shaft 40 has a slot at the exposed end of the threaded
shaft to allow screwdriver adjustment of the laser mirror 39. If
necessary, the shaft and mating threaded port in the container may
include a rotating seal to better retain a vacuum or pressure in
the cavity 17a. It should be noted that FIG. 2 is not drawn to
scale to better illustrate the laser-related components which are
generally smaller than shown.
FIG. 3 shows a schematic front cross sectional view of a second
alternative embodiment of the sample chamber 14b. The open sided
container 15b extends to the microscope glass slide 35a instead of
the encased sample 31 as shown in FIG. 2. The encased sample 31 is
again pressed against clay 36 in a fixtured press to obtain a
repeatable height and orientation of the exposed surface 34 of
sample 32. The location of the surface 34 is at the common focal
height with respect to the microscope 16 and laser spot focusing
systems when the chamber is nearly enclosed or forming a boundary
for the effluent gases.
Through the microscope 16, the observer selects a particle of
interest and identifies the relationships with adjoining particles.
The observer then selects the spot on the particle of interest
within the exposed surface of sample 32 to be analyzed by
pyrolysis. Focusing the visible laser beam 3 (see FIG. 1 and
narrowing lines "d" shown on FIG. 3) on the selected particle spot
is accomplished by adjusting threaded shaft 40 and attached mirror
39 (or moving the particle to the center of the field of view)
while observing through the optical window 30 and microscope 16.
The near-infrared laser 6 (see FIG. 1) heats and pyrolyzes a 10
micron sized spot on the selected particle at the exposed surface.
The observation, selection and spot pyrolysis is repeated at
another portion of the same (or different) particle. Multiple laser
heating bursts can be used to obtain a minimum resolution amount of
pyrolyzates from the same particle, or the same type of particle,
required by the chemical pyrolyzate analysis devices (see FIG.
1).
FIG. 4 shows a schematic side cross sectional view 4--4 of the
second alternative sample chamber 14b shown in FIG. 3. The sample
chamber 14b comprises the container 15b and attachment element 43.
The attachment element 43 attaches container 15 to the objective
lens barrel of microscope 16. The attachment element 43 places the
sample chamber 14b so that focusing motion of the glass slide 35a
also brings a sample surface into a common focus and sealed
position.
The open ended container 15b has supply port 41 through which inert
gas (from piping 18 and inert gas supply 19 shown in FIG. 1) is
provided to the cavity 17b. The supply piping 19 shown in FIG. 2
extends to a point near the spot at the central portion of the
cavity 17b to improve gas sweeping into the collection piping 20.
Alternative construction would also comprise fittings attached to
the container 15b and a flexible extension of the supply piping
within the cavity.
The collection system piping 20 and the protruding piping portion
25 pass through a collection port 42. The collection port 42
includes a thermal insulation 44. The thermal insulation is
composed of a ceramic material, but may be any other insulation
material or structure capable of withstanding elevated temperatures
needed to prevent condensation of pyrolyzate gases, approximately
290.degree. C. in the embodiment shown in FIG. 4, and structurally
capable of withstanding any expected pressure or vacuum within the
cavity 17b. The insulated design of the collection port 42 and
thermal contact between interior and exterior (to the container)
portions of the collection piping, allow the resistance heater 21
(see FIG. 1) to heat the collection piping 20 including the
protruding section (or chamber interior portion) 25 by conduction.
The laser window 38 is centrally located on one side to point the
laser beam onto the adjustable mirror, thereby reflecting the beam
onto the exposed surface of the encased sample 31. The protruding
portion 25 of the collection piping is also located proximate to
the laser impingement spot on the encased sample 31. Although
collection piping and the supply piping is shown in FIG. 4
extending to the front and rear, respectively, of the chamber,
alternative embodiments can place the piping and ports in other
locations, angles or orientations within the chamber.
FIG. 5 is a sectioned perspective view of the chamber 14b shown in
FIGS. 3 and 4. The attachment member 43 can be strapped to the
microscope lens barrel. The strapped position again obtains a
common focal plane/spot when the end seal 33 abuts the glass slide
35a (see FIG. 3) to seal cavity 17b from the bottom. Protruding
into cavity 17b are sections of inert gas piping 18 and collection
piping 20. The collection piping 20 is thermally insulated from
container 15b. A laser window 38 covers another aperture in the
walls of container 15b, which is aligned so that the laser beams
(see FIG. 3) reflected from laser mirror 39 onto a plane parallel
to the exposed surface of the sample (see FIG. 3). Window 30 covers
still another container 15b aperture at the top near the
microscope.
FIG. 6 is a perspective view of the preferred embodiment of the
sample chamber portion of the apparatus. The objective lens barrel
45 of the microscope 16 is attached to an attach member 43a.
Attachment supports a tubular or duct-like container 15c in a
position just above the focal plane (and coincident with the
exposed sample surface 34) of the microscope. This position is also
coincident with focal spot "e" at the end of the converging laser
beam "d". Alternative embodiments may strap the attach member 43a
to the lens barrel of the microscope. The lens barrel 45 of
microscope 16 holds an objective lens 46 proximate to the sample
surface 34 at a distance "b" (see FIG. 2).
The tubular chamber 15c has a lower aperture 47 shaped and
dimensioned to partially abut the contact sample surface 34 when
the chamber 14c is lowered or sample surface 34 raised. The abutted
position is not designed to create an absolutely fluid tight seal
of the cavity 17c. The position need only to restrict and minimize
the loss at the abutted interface of inert gas flow (shown as an
inflow arrow) from inert gas piping 18 when compared to the amount
of inert gas flow recovered (shown as outflow arrow) in collection
piping 20. A small relative loss of pyrolyzate (and inert) gas at
the abutted interface does not significantly impair the analysis of
the pyrolyzate gas.
The ceramic insulation 44 again insulates and supports the
collection piping portion protruding (shown dotted) into the
tubular chamber 15c. Protruding portion extends to nearby the
sealing or contacting aperture 47, proximate to the particle of
interest on the sample surface 34 of sample 32. The insulated
collection piping can be either conductively heated (to prevent gas
condensation) or cooled (to trap pyrolyzate gases while allowing
the inert gases to pass through).
The tubular shape of the container 15c further assists in the
sweeping and collection of pyrolyzate gases. The tubular chamber is
composed of quartz or other material transparent to optical and
near-infrared frequency radiations. The tubular shape also presents
a nearly perpendicular surface to vertical (visible) radiations to
the lens barrel of the microscope 16 and reflected near-infrared
laser beam "d" from laser mirror 39. The entire quartz tubular
container 15c may also be heated (or cooled) and the aperture
sealed with an elastomeric O-ring if reductions in the loss of
pyrolyzate gases are required.
A silicone plug 48 joins the end of tubular container 15c and
supply piping systems 18. Alternative embodiments can also extend
the gas supply piping 18 into the tubular chamber 15c similar to
the prior alternative embodiments. In addition, the portion of the
collection piping 20 protruding into the tubular chamber 15c can be
deleted if the container's tubular shape, heating or cooling, or
aperture sealing collects a sufficient fraction of the pyrolyzates
generated by the laser beam "d".
The height "f" of attachment member 43a provides a set-off distance
from the objective lens 46 to the sample surface 34. This set-off
distance places the sample surface 34 proximate to aperture 47 in
the focal plane of the microscope lenses and coincident with the
focal spot "e" when the aperture is in contact with sample surface
34.
FIG. 7 is a cross sectional view 7--7 as shown on FIG. 6 of the
preferred tubular chamber. Laterally moving the particle of
interest 49 can place it directly under the aperture 47 of the
tubular chamber 15c. The tubular chamber is slightly bent near the
aperture 47 to direct (sweep) inert gas flow (inflow arrow) from
gas supply piping system 18 across the aperture 47 and the particle
of interest 49. The shape of tubular container and collection
piping 20 collects swept inert and pyrolyzate gases into the trap
(see FIG. 1). The aperture is shaped to contact the exposed surface
34 of the sample 32. The aperture 47 is also shaped and dimensioned
to place the particle of interest within the focal plane/spot of
the microscope and laser systems (see FIG. 1). Alternative
embodiments can include straight duct-like chambers or non-circular
cross-sectional duct dimensions.
The operational process of using the preferred embodiment of the
analyzer chamber shown in FIGS. 6 and 7 first encases and polishes
the sample surface containing the particle(s) of interest. The
composite sample is attached by compressing putty against a glass
slide using a stop fixture and a pressing tool to orient and
position the polished surface. Raising the attached sample (i.e.,
raising the microscope stage) abuts the sample surface against the
contact surface (opening or aperture edges 49) of the tubular
chamber 15c. The polished surface 34 forms a low gas loss interface
to generally enclose any pyrolyzate effluents within the tubular
chamber 15c.
The height of the abutting surface of the chamber 15c acts as a
measured set-off distance spacer, putting the sample surface into
the optical focal plane of maximum optical detection sensitivity.
The operator then scans the sample surface 34 within the
microscope's field of view and selects a spot as small as 10
microns on the particle of interest 49. The visible laser beam (see
FIG. 1) and a laser mirror are adjusted to place the visible laser
beam onto the selected spot.
The chamber is purged, and the near infrared laser duration and
intensity controls selected. The selected duration and intensity of
the laser beam must expose the particle to sufficient absorbed
energy to generate a gaseous pyrolyzate from the 10 micron spot on
the particle. The depth of pyrolysis of the sample is a function of
laser beam intensity and duration, as well as the absorption
characteristics of the particle. After and during laser heating,
the generated pyrolyzate gases are sucked along with an inert gas
to a cold trap, which passes the inert carrier gas but condenses
the pyrolyzate gases.
Sufficient pyrolyzate quantities are collected in the cold trap by
repeating the procedure at different spots (or to a different
depth). The quantity collected is sufficient for analysis by a gas
chromatograph and mass spectrometer. When analysis is desired, the
coolant supply to the cold trap is removed. Increasing the gas
chromatograph oven temperature moves the pyrolyzate gases through
the gas chromatograph's capillary column at a rate dependent upon
their molecular weight and vapor pressure. The optical information
and analysis of the pyrolyzate compounds determine the composition
and properties of the particle of interest.
The advantages of this device and method include: an ability to
optically and thermally analyze an entire or portion(s) of a single
small microscopic-sized particle or type of small particle; the
flexibility to analyze or store multiple quantities of pyrolyzate
from a particle; accomplishing the focus and enclosing of the
sample in a single step; the prevention of pyrolyzate gas loss by
the chamber shape and conduction heating of the protruding
collection tube; and avoiding design compromises of the prior
microscope and laser systems.
Still other alternative embodiments of the invention are possible.
These include: incorporating the microscope lens as part of the
chamber enclosure (i.e., extending the chamber to seal against the
lens or lens barrel of the microscope); providing an unattached or
non-encased sample (i.e., a sample placed, but not attached to a
glass slide); providing the duct-like tube within a second chamber
such as placing the duct-like chamber 15c shown in FIG. 7 within
the chamber 15a shown in FIG. 2, (to further sweep and direct gas
flows); colinearly transmit the microscope's field of view and
laser beams through a single window; and replacing the abutting
chamber end contact surface with an aperture having a
circumferential edge contact surface with the sample (i.e., the
aperture shaped to act as a sliding ring seal or closely spaced
apart surface around the edge diameter of the sample), allowing
further focal adjustment without loss of a sealed chamber or a high
loss of fluid.
While the preferred embodiment of the invention has been shown and
described, and some alternative embodiments also shown and/or
described, changes and modifications may be made thereto without
departing from the invention. Accordingly, it is intended to
embrace within the invention all such changes, modifications and
alternative embodiments as fall within the spirit and scope of the
appended claims.
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